An Early Experiment Hinting at DNA

Anomaly (2) was observed by Fred Griffith, decades before DNA and the genetic code. He found that if you inject a heat-treated, dead, virulent species of bacteria (pneumococcus S) into a rat previously infected with a nonvirulent species (pneumococcus R), then species R became transformed into species S, thereby killing the rat. About fifteen years later, Oswald Avery found that you can even do this in a test tube; dead S would transform live R into live S if the two were simply incubated tog...

 Evolution Can Only Build on What is Already There

To produce a really good biological theory one must try to see through the clutter produced by evolution to the basic mechanisms lying beneath them, realizing that they are likely to be overlaid by other, secondary mechanisms. What seems to physicists to be a hopelessly complicated process may have been what nature found simplest, because nature could only build on what was already there.

 The Sequence Hypothesis and The Central Dogma

My own thinking (and that of many of my colleagues) is based on two general principles, which I shall call the Sequence Hypothesis and the Central Dogma. The direct evidence for both of them is negligible, but I have found them to be of great help in getting to grips with these very complex problems. I present them here in the hope that others can make similar use of them. Their speculative nature is emphasized by their names. It is an instructive exercise to attempt to build a useful theory ...